Application of low tube voltage and low volume contrast medium protocol on 128-slice dual-source CT in children with tetralogy of Fallot / 中华放射学杂志

ABSTRACT

Objective To investigate the effectiveness and feasibility of cardiovascular computed tomography angiography(CTA) in 128-slice DSCT with low tube voltage and low dosage contrast media in children with tetralogy of Fallot (TOF). Methods Forty patients with TOF were randomly divided into group A and group B by random number table method, patients in group A received a conventional scan with 80 kVp and contrast media of 1.2 ml/kg, patients in group B, 70 kVp and contrast media of 1.0 ml/kg were used. The injection time of the two groups were both fixed for 12 s. CT attenuation, image noise and signal-to-noise ratio (SNR) of ascending aorta, the main pulmonary artery, left ventricle and right ventricle were quantified. Radiation dose and volume of the contrast medium were recorded. Subjective image quality was assessed by two radiologists in consensus. The Student's t test was performed to analyse the differences between the two groups regarding CT attenuation, image noise, SNR, radiation dose and volume of the contrast medium. The image quality scores between the two groups were compared by using the Mann-Whitney U test. Results No significant difference was found in the attenuation, noise, SNR between the two groups in the same evaluated anatomic regions and no significant difference was found in the image quality. Effective dose (ED) was(0.17±0.05),(0.13±0.04)mSv respectively, there was significant reduction in group B than that in group A (t=2.48, P=0.019). The consumed iodine amount was(10.00±1.84),(8.29± 1.45) ml respectively, there was significant reduction between the two groups (t=2.89, P=0.007). Conclusions In children with TOF, the cardiovascular CTA with diagnostic quality can be adequately acquired with low tube voltage (70 kVp) and low concentration contrast media (1.0 ml/kg), there is significant reduction in radiation dose and contrast medium amount.